a) Field of the Invention
This invention relates to a tube-pressed brake suitable for use in a clutch or brake of an automatic transmission, construction machinery, agricultural machinery or the like.
b) Description of the Related Art
FIG. 1 is a cross-sectional view, as viewed from the front, of a tube-pressed brake before the present invention is applied. A tube 1 is arranged on and along an inner periphery of an outer frame 2, and is folded back at opposite end portions thereof. Folded portions 3 are fixed on the outer frame 2 by presser plates 4 and rivets 5, respectively. Designated at numeral 7 is a pressure fluid supply hole formed through the outer frame 2 to inject a pressure fluid into the tube. Numeral 7 indicates an opening of the outer frame 2. The tube 1 is folded back at the opposite end portions thereof over edge portions of the opening 7, respectively. Incidentally, a counterpart member to be bound is located inside the tube 1 although this counterpart member is not illustrated in the drawing.
Rubber or the like is primarily used as the material of the tube of the tube-pressed brake. Conventionally, such rubber-made tubes have been used as they are.
A tube for use in a tube-pressed brake is desired to be equipped with improved heat resistance, strength and friction characteristic and also with improved basic performances for the prevention of occurrence of drag torque and the prevention of leakage of a pressure fluid. Conventional tubes, which make use of rubber or the like as they are, are however not fully satisfactory in this respect.
With the foregoing in view, the present invention has as an object the provision of a tube-pressed brake in which a tube is improved in such properties and performances.
As a result of extensive research, the present inventors have found that the above object of the present invention can be achieved by applying a coating to the tube.
In one aspect of the present invention, there is thus provided a tube-pressed brake comprising a tube for being injected with a pressure fluid to produce a pressure therein to permit transmission of a torque between two members arranged in a combination and rotating relative to each other, wherein the tube has been applied with a coating. The coating may be applied on either an inner wall or outer wall of-the tube. The tube-pressed brake may further comprises a circular frame member wits an opening formed therethrough, wherein the tube is folded back at opposite end portions thereof over edges of the opening, respectively, such that the tube is held in place on the frame member, and the tube has been applied with coatings at respective folded portions thereof.
Owing to the provision of the coating, the tube-pressed brake according to the present invention can prevent the tube from coming into contact with a counterpart member, which would otherwise take place as the tube may slack and fail to retain its shape when the tube-pressed brake is released. The coating can also prevent leakage of the pressure fluid. In addition, the coating makes it possible to adjust friction characteristics of the tube. The tube-pressed brake is therefore equipped with improved heat resistance and strength.